diff --git a/libs/ktem/ktem/index/file/graph/lightrag_pipelines.py b/libs/ktem/ktem/index/file/graph/lightrag_pipelines.py
index ffc92b8..7fe1ad9 100644
--- a/libs/ktem/ktem/index/file/graph/lightrag_pipelines.py
+++ b/libs/ktem/ktem/index/file/graph/lightrag_pipelines.py
@@ -259,6 +259,7 @@ class LightRAGIndexingPipeline(GraphRAGIndexingPipeline):
                 if all(
                     keyword not in prompt_name.lower() for keyword in blacklist_keywords
                 )
+                and isinstance(content, str)
             }
         except ImportError as e:
             print(e)
diff --git a/libs/ktem/ktem/index/file/graph/nano_pipelines.py b/libs/ktem/ktem/index/file/graph/nano_pipelines.py
index 438877f..0a4b4ab 100644
--- a/libs/ktem/ktem/index/file/graph/nano_pipelines.py
+++ b/libs/ktem/ktem/index/file/graph/nano_pipelines.py
@@ -255,6 +255,7 @@ class NanoGraphRAGIndexingPipeline(GraphRAGIndexingPipeline):
                 if all(
                     keyword not in prompt_name.lower() for keyword in blacklist_keywords
                 )
+                and isinstance(content, str)
             }
         except ImportError as e:
             print(e)